Compilation errors on Guix

[rxt1077]

When compiling for Guix the linker gives errors:

ryan@wtp /tmp/dmrconfig$ make CC=gcc
gcc -g -O -Wall -Werror  -DVERSION='"1.1.258"' -I/gnu/store/xk3b7p8kk4lq696sdkw7v11hxjv12s5g-libusb-1.0.25/include/libusb-1.0   -c -o main.o main.c
gcc -g -O -Wall -Werror  -DVERSION='"1.1.258"' -I/gnu/store/xk3b7p8kk4lq696sdkw7v11hxjv12s5g-libusb-1.0.25/include/libusb-1.0   -c -o util.o util.c
gcc -g -O -Wall -Werror  -DVERSION='"1.1.258"' -I/gnu/store/xk3b7p8kk4lq696sdkw7v11hxjv12s5g-libusb-1.0.25/include/libusb-1.0   -c -o radio.o radio.c
gcc -g -O -Wall -Werror  -DVERSION='"1.1.258"' -I/gnu/store/xk3b7p8kk4lq696sdkw7v11hxjv12s5g-libusb-1.0.25/include/libusb-1.0   -c -o dfu-libusb.o dfu-libusb.c
gcc -g -O -Wall -Werror  -DVERSION='"1.1.258"' -I/gnu/store/xk3b7p8kk4lq696sdkw7v11hxjv12s5g-libusb-1.0.25/include/libusb-1.0   -c -o uv380.o uv380.c
gcc -g -O -Wall -Werror  -DVERSION='"1.1.258"' -I/gnu/store/xk3b7p8kk4lq696sdkw7v11hxjv12s5g-libusb-1.0.25/include/libusb-1.0   -c -o md380.o md380.c
gcc -g -O -Wall -Werror  -DVERSION='"1.1.258"' -I/gnu/store/xk3b7p8kk4lq696sdkw7v11hxjv12s5g-libusb-1.0.25/include/libusb-1.0   -c -o rd5r.o rd5r.c
gcc -g -O -Wall -Werror  -DVERSION='"1.1.258"' -I/gnu/store/xk3b7p8kk4lq696sdkw7v11hxjv12s5g-libusb-1.0.25/include/libusb-1.0   -c -o gd77.o gd77.c
gcc -g -O -Wall -Werror  -DVERSION='"1.1.258"' -I/gnu/store/xk3b7p8kk4lq696sdkw7v11hxjv12s5g-libusb-1.0.25/include/libusb-1.0   -c -o hid.o hid.c
gcc -g -O -Wall -Werror  -DVERSION='"1.1.258"' -I/gnu/store/xk3b7p8kk4lq696sdkw7v11hxjv12s5g-libusb-1.0.25/include/libusb-1.0   -c -o serial.o serial.c
gcc -g -O -Wall -Werror  -DVERSION='"1.1.258"' -I/gnu/store/xk3b7p8kk4lq696sdkw7v11hxjv12s5g-libusb-1.0.25/include/libusb-1.0   -c -o anytone_ht.o anytone_ht.c
gcc -g -O -Wall -Werror  -DVERSION='"1.1.258"' -I/gnu/store/xk3b7p8kk4lq696sdkw7v11hxjv12s5g-libusb-1.0.25/include/libusb-1.0   -c -o dm1801.o dm1801.c
gcc -g -O -Wall -Werror  -DVERSION='"1.1.258"' -I/gnu/store/xk3b7p8kk4lq696sdkw7v11hxjv12s5g-libusb-1.0.25/include/libusb-1.0   -c -o hid-libusb.o hid-libusb.c
gcc -g -o dmrconfig main.o util.o radio.o dfu-libusb.o uv380.o md380.o rd5r.o gd77.o hid.o serial.o anytone_ht.o dm1801.o hid-libusb.o -L/gnu/store/xk3b7p8kk4lq696sdkw
7v11hxjv12s5g-libusb-1.0.25/lib -lusb-1.0
ld: serial.o: in function `find_path':
/tmp/dmrconfig/serial.c:366:(.text+0x73e): undefined reference to `udev_new'
ld: /tmp/dmrconfig/serial.c:373:(.text+0x74e): undefined reference to `udev_enumerate_new'
ld: /tmp/dmrconfig/serial.c:374:(.text+0x75e): undefined reference to `udev_enumerate_add_match_subsystem'
ld: /tmp/dmrconfig/serial.c:375:(.text+0x766): undefined reference to `udev_enumerate_scan_devices'
ld: /tmp/dmrconfig/serial.c:377:(.text+0x76e): undefined reference to `udev_enumerate_get_list_entry'
ld: /tmp/dmrconfig/serial.c:431:(.text+0x77e): undefined reference to `udev_enumerate_unref'
ld: /tmp/dmrconfig/serial.c:432:(.text+0x786): undefined reference to `udev_unref'
ld: /tmp/dmrconfig/serial.c:381:(.text+0x7ea): undefined reference to `udev_list_entry_get_next'
ld: /tmp/dmrconfig/serial.c:384:(.text+0x7fa): undefined reference to `udev_list_entry_get_name'
ld: /tmp/dmrconfig/serial.c:385:(.text+0x805): undefined reference to `udev_device_new_from_syspath'
ld: /tmp/dmrconfig/serial.c:390:(.text+0x81a): undefined reference to `udev_device_get_parent_with_subsystem_devtype'
ld: /tmp/dmrconfig/serial.c:398:(.text+0x82a): undefined reference to `udev_device_get_devnode'
ld: /tmp/dmrconfig/serial.c:402:(.text+0x83b): undefined reference to `udev_device_get_sysattr_value'
ld: /tmp/dmrconfig/serial.c:403:(.text+0x84b): undefined reference to `udev_device_get_sysattr_value'
ld: /tmp/dmrconfig/serial.c:425:(.text+0x89c): undefined reference to `udev_device_unref'
ld: /tmp/dmrconfig/serial.c:431:(.text+0x8b0): undefined reference to `udev_enumerate_unref'
ld: /tmp/dmrconfig/serial.c:432:(.text+0x8b8): undefined reference to `udev_unref'
collect2: error: ld returned 1 exit status
make: *** [Makefile:53: dmrconfig] Error 1

This is because the Makefile doesn't add -ludev to LIBS if it can't find the static version of libusb-1.0.
PR to follow.